Purification and some properties of threonine dehydratase from Candida maltosa

✍ Scribed by Doz. Dr. R. Bode; I. Schult; D. Birnbaum

• Publisher: John Wiley and Sons
• Year: 1986
• Tongue: English
• Weight: 618 KB
• Volume: 26
• Category: Article
• ISSN: 0233-111X
• DOI: 10.1002/jobm.3620260802

✦ Synopsis

Threonine dehydratase has been purified about 200-fold from extracts of Candida maltosa by chromatography on DEAE-cellulose, Sephadex G-200, and hydroxylapatite. The enzyme is fairly stable in solution in the presence of 250 mM phosphate buffer containing 40% glycerol. The molecular weight of the native enzyme was calculated t o be approximately 190,000. The molecular weight of a subunit of the enzyme was estimated t o be 46,000 by SDS gel electrophoresis. The enzyme seemed to have a tetrameric structure consisting of four identical subunits. The enzyme is subject t o feedback inhibition by isoleucine and is stimulated by valine and phosphate ions. Kinetic studies indicate that there are more than one binding site for each effector on the enzyme. It is concluded from these investigations that the binding sites for threonine as well as for isoleucine are diatinct from another, whereas the binding sites for valine and phosphate are identical or closely overlapping.